Interchangeable holder for hollow drills

ABSTRACT

The invention relates to an interchangeable holder ( 1 ) for hollow drills, comprising a support element ( 4 ) for receiving a base end ( 11 ) of a drill rod ( 10 ) of the hollow drill on a front face, and a holding device ( 12 ) for a handle of the support element ( 4 ) on associated recesses ( 15 ) that are configured in the wall of the drill rod ( 10 ) on its base end ( 11 ). The aim of the invention is to provide a universal interchangeable holder on which drill rods with different diameters can be mounted. To this end, the support element ( 4 ) has a front-face annular rest zone ( 9 ) that receives drill rods ( 10; 10′; 10 ″) with different diameters. A locking device ( 24 ), together with the holding device ( 12 ), is effecitve across the width of the annular rest zone ( 9 ) in order to maintain the respective drill rod ( 10; 10′; 10 ″) placed on the rest zone ( 9 ) and held by the holding device ( 12 ) locked in a center position.

[0001] The invention relates to an interchangeable holder for hollowdrills, containing a carrier part for end accommodation of the base endof the drill rod of the hollow drill, and a holding means for retainingengagement of the carrier part on the assigned recesses which are madein the wall of the drill rod on its base end.

[0002] The invention relates furthermore to a hollow drill for fixing onan interchangeable holder, the drill rod of the hollow drill having onthe base end opposite the drill tip recesses for producing bayonet-likeretaining engagement to a holding means of the interchangeable holderand each recess having an entry section for the holding means.

[0003] DE 198 18 284 A1 discloses a core cutting tool for masonry with ainterchangeable holder which has a carrier disk with a central hollowjournal which can be fixed on the hollow shaft which can be clamped in adrill chuck for driving the carrier disk. The carrier disk contains onits end face which is opposite the journal, which is perpendicular tothe axis of rotation, and which forms a contact surface for a hollow rodof the core cutting tool, an outer annular wall which is located on theperiphery of the carrier disk, a middle annular wall which is located ata short distance from the outer wall, and an inner annular wall. Threeholding pins run radially from the inner wall through the middle wall tothe outer wall, their being located spaced apart from the end face andoffset by 120° each against one another. The hollow rod contains on itsbase end opposite the cutting teeth three L-shaped slots which arelocated offset by 120° on the periphery of the hollow rod and with theholding pins of the hollow rod which adjoins the end face of the carrierdisk form a quarter-turn fastener. Here the inside of the hollow roddirectly borders the outside of the middle annular wall and the bracketsformed by the L-shaped slots press elastically against the outside ofthe middle annular wall so that the hollow rod is held centrally on thecarrier disk. On the bracket a projection can be formed which can fitinto the assigned recess in the outside of the middle annular wall andthus can form an interlock of the hollow rod on the carrier disk. Thiscore cutting tool is designed to hold a hollow rod of a certain diameterwhich directly extends over the middle annular wall. There is noaccommodation of hollow rods with diameters which differ arbitrarilywithin a range and due to the type of interlocking of the brackets whichrequire direct contact against the outside of the middle annular wall,there can be no accommodation.

[0004] The object of the invention is to devise the interchangeableholder mentioned initially which allows simple, centering attachment ofthe drill rods of drilling tools or cutting tools even with differentdiameters, and a hollow drill for this interchangeable holder.

[0005] This object is achieved as claimed in the invention in theaforementioned interchangeable holder in that the carrier part has anend annular contact area for accommodating drill rods with differentdiameters and that there is a locking means which together with theholding means is active over the width of the annular contact area inorder to keep locked in the centered position the drill rod which isheld by the holding means and which has been placed against the contactarea. This configuration enables drill rods with different diameters tobe detachably mounted on the interchangeable holder, the drill rods ontheir back connecting or base ends requiring, instead of complexcoupling or adapter parts or the like, simply recesses formed in thewall for engaging the holding means. Thus, one such drill rod can beeconomically produced. Furthermore, one such interchangeable holder canbe used for a larger range of drill diameters and drill rod diameters.Drill rods with diameters which are arbitrary within the allowable rangecan be kept centered and locked by the locking means which is providedon the carrier part. The interchangeable holder is generally suitablefor any type of drilling and cutting tools, the term hollow drill forexample also including compass saws.

[0006] Advantageous embodiments of the invention are given in thedependent claims.

[0007] One simple configuration calls for the holding means to have atleast two and especially three roughly radially arranged holding pinsfor bayonet-like retaining engagement in the assigned recesses on thebase end of the drill rod. For two holding pins located on a straightline the drill rod must be separately centered when fixed. For threepins which are located radially to one axis of rotation and especiallyat the same interval of 120° to one another centering necessarily takesplace when the drill rod is attached to the holding means or the holdingpins. However there can also be more than three holding pins or elementsof the holding means which allow the drill rod to be centered and fixed.

[0008] Feasibly the locking means for each holding pin contains amovable locking tooth, and the locking teeth for locking the drill rodwhich is held by the holding pins can be extended out into the recesses.The locking teeth which are located in the recesses prevent the drillrod from being able to turn relative to the holding pins. In this waythe drill rod is securely fixed. The locking teeth are formed forexample as plates.

[0009] Preferably each locking tooth is formed such that it extendsroughly over the free length of the holding pin and can be extendedthrough a slotted opening which has been formed in the contact surfaceof the carrier part in the axial direction into a position which bordersthe holding pin. The width of the opening is formed such that thelocking tooth is guided almost without play in the opening. On the otherhand, the opening can be wider than the shaft of the locking tooth sothat the locking tooth with this play can be pushed in the opening suchthat it cannot be jammed by fine drilling material.

[0010] If the annular contact area or the annular end contact surface ofthe carrier part is bordered by an outer boundary and an inner boundary,the holding pins can each be supported on the outside boundary and theinside boundary and each locking tooth extends in an arrangement whichis offset parallel to its holding pin roughly over the free length ofthe holding pin which is effective for the holding means.

[0011] The locking teeth can be supported to be able to moveindividually. Preferably however the interchangeable holder contains alocking carrier which is supported to be axially movable on the centralshaft of the carrier part and which contains the locking means or theaxially projecting locking teeth. This facilitates handling of theinterchangeable holder.

[0012] This locking carrier is feasibly pretensioned elastically againstthe carrier part in the locked position so that for example locking isfacilitated by spring force.

[0013] If each locking tooth is rounded or beveled towards its end face,the locking tooth easily finds its locking engagement.

[0014] Movement into locking engagement is further supported if eachrecess on the drill rod has an entry section for the holding pin and thelocking tooth and if the entry section has at least one side edge whichis tilted towards the direction of motion of the locking tooth and whichacts in the manner of a funnel-like guide.

[0015] Feasibly, each holding pin is held stationary in the carrier partor in the inner boundary and in the outer boundary in the assignedholes. In order to facilitate dismounting of the holding pin from thecarrier part, it can be provided that for each holding pin coaxialthrough holes are formed in the opposite section of the carrier part, bywhich the holding pin which sits securely in its bearing holes can beknocked out by means of an arbor.

[0016] To prevent the opened locking means from locking unintentionallyunder the high spring force of the tensioning spring before a drill rodis attached, there can be a catch means for fixing the opened lockingcarrier on the carrier part in the catch position.

[0017] In order to facilitate replacement and fixation of differentdrill rods, in the aforementioned hollow drill it is provided as claimedin the invention that the entry section has at least one side edge whichis especially bevelled and/or rounded and tilted to the axis ofrotation. The tilted side edge supports the insertion of the lockingmeans in the entry section when the drill rod is not exactly alignedwhen mounted on the interchangeable holder. The tilted side edge offersa funnel-like support which is improved by a configuration with twotilted or bevelled side edges which lie opposite one another on theentry section. Feasibly the entry section contains a locking section andthe tilted side edge is opposite the locking section.

[0018] The angle between the bevelled side edge and a line parallel tothe axis of rotation is preferably roughly 30° to 45° and if necessarycan be chosen to be smaller or larger.

[0019] One embodiment of the interchangeable holder with the drill rodof a hollow drill is detailed below with reference to the drawings.

[0020]FIG. 1 shows in an axial top view a interchangeable holder forhollow drills, three drill rods with different diameters being shown forillustration;

[0021]FIG. 2 shows in a sectional view along the cut plane A-A shown inFIG. 1 the interchangeable holder with the three drill rods;

[0022]FIG. 3 shows in an axial top view a locking means of theinterchangeable holder;

[0023]FIG. 4 shows the locking means in a sectional view along the cutplane B-B shown in FIG. 3;

[0024]FIG. 5 shows the locking means shown in FIG. 3 in a side view;

[0025]FIG. 6 shows in a side view a drill rod with a recess formed onthe base end of the drill rod for engagement for the locking means;

[0026]FIG. 7 shows in an axial top view the base end of the drill rodshown in FIG. 5.

[0027]FIG. 8 shows a recess on the base end of the drill rod with aholding means and with a locking means in locking engagement in a sideview, enlarged; and

[0028]FIG. 9 shows a modified locking tooth in locking engagement in aview as shown in FIG. 8.

[0029] A interchangeable holder 1 for hollow drills contains a shaft 2(see FIGS. 1 and 2) with a central axial hole 3 and a disk-shaped axialcarrier part 4 which is securely mounted on the shaft 2 and is madeintegral with it. The carrier part 4 has an annular recess 5 which isformed in the axial direction and which is bordered radially on theinside by the front end 6 of the shaft 2 and on the outside by aperipheral outside wall 7. The bottom of the recess 5 forms an annular,end contact surface 9 which is perpendicular to the axis 8 of rotationof the interchangeable holder 1 and against which the drill rod 10 of ahollow drill can be axially placed with its base end 11 which isopposite the drill crown. The diameter of the drill rod 10 which can beattached to the interchangeable holder 1 is in the range between theinside diameter of the outside wall 7 and the outside diameter of thefront end 6 of the shaft 2. For example, in FIGS. 1 and 2 two differentdrill rods 10′ and 10″ are shown in addition, of which the drill rod 10′has a maximum possible diameter of for example 100 mm and adjoins theoutside wall 7, while the drill rod 10″ has a roughly minimum diameterof for example 40 mm and extends over the front end 6 of the shaft 2with little play.

[0030] The interchangeable holder 1 contains three holding pins 12 whichform a holding means for the drill rod 10 and which are aligned radiallywith respect to the axis 8 of rotation, are spaced uniformly apart fromone another over the periphery and are securely mounted in therespective radial holes 13 on the front end 6 of the shaft 2 and inassigned radial holes 14 in the outside wall 7 of the carrier part 4.The three holding pins 12 are located in the plane which is parallel tothe contact surface 9 and are spaced apart from the contact surface 9(see FIG. 2). For each holding pin 12, coaxially to its bearing holes 13and 14 in the opposing section of the carrier part 4 holes 13′ and 14′are formed, through which the holding pin 12 can be knocked out by meansof an arbor, if it would have to be replaced.

[0031] The drill rod 10 which is to be mounted on the interchangeableholder 1 contains on its base end 11 (see FIG. 6) three recesses 15which are spaced uniformly over the periphery of the drill rod 10. Eachrecess 15 contains an entry section 17 which is opened toward the endface 16 of the base end 11, and a locking section 18 which extends fromthe entry section 17 as an undercut in the peripheral direction of thedrill rod 10 and forms a locking projection 19 in the wall of the drillrod 10. The recesses 15 with their locking sections 18 and lockingprojections 19 together with the holding pins 12 form a holding means inthe manner of a quarter-turn fastener. The entry section 17 is madetapered by a side edge 20 which is bevelled in a top view and which isopposite the locking section 18 so that it is wider on the end openingthan on its inner base 21.

[0032] The disk-shaped carrier part 4 on each holding pin 12 contains aslotted through opening 22 which offset in an axial top view is locatednext to the holding pin 12 and parallel to it, extends axially throughthe disk-shaped carrier part 4, reaches inside toward the axis 8 ofrotation as far as the shaft 2 and on the outside as far as to or intothe outside wall 7, and thus extends over the annular contact surface 9.In each opening 22 a locking tooth 24 which projects from a lockingcarrier 23 in the axial direction is movably held. The locking carrier23 is formed to be disk-shaped and is movably arranged by means of acentral bearing opening 25 on the shaft 2. A helical spring 26 which issupported on the shaft 2 pretensions the locking carrier 23 against theback 27 of the carrier part 4 in the locking position. By means of anannular holding collar 28 with an outside peripheral recess for manualcontrol, the locking carrier 23 can be pushed manually against thetensioning force of the helical spring 26 out of the locked position asshown in FIG. 2 into the unlocked position, in which the locking teeth24 are pulled back and their end faces 29 are arranged at least flatwith the annular contact surface 9 or are set back from it. A pot-likecover sleeve 30 which is mounted on the shaft 2 covers the helicalspring 26 and is surrounded by the holding collar 28 on the lockingcarrier 23.

[0033] For mounting and fixing a drill rod 10 on the interchangeableholder 1, first the locking carrier 23 is pulled back against the forceof the helical spring 26 until the locking teeth 24 have been pulledcompletely out of the openings 22 in the carrier part 4. The lockingcarrier 23 can now be turned relative to the carrier part 4 so that thelocking teeth 24 adjoin the back 27 of the carrier part 4 and thelocking carrier 23 is held in the unlocked position. A journal 31 whichprojects from the end face 29 of one of the locking teeth 24 can fitinto the assigned recess 32 on the back 27 of the carrier part 4 so thatthe locking carrier 23 is secured against unintentional turning in itsunlocked position. The drill rod 10 which is designed for attachment isnow moved with its base end 11 in this position against the contactsurface 9 and is placed against it such that the holding pins 12 areinserted into the assigned recesses 15. If the drill rod 10 adjoins thecontact surface 9, it is turned around its lengthwise axis until all theholding pins 12 are held in the respective locking sections 18 of therecesses 15. The three holding pins 12 which are arranged each offset by120° center the drill rod 10 on the carrier part 4. Then the lockingcarrier 23 is turned out of its catch position until the locking teeth23 are located in front of the openings 22 and move jointly with thelocking carrier 23 which is moved by spring force through it. Eachlocking tooth 23 moves into the entry section 17 of the recess 15, theinsertion into the entry section 17 being supported by its bevels 33 onthe end face 29 and by the bevelled side edge 20. The bevelled side edge20 furthermore causes the drill rod 10 to be moved into its correctholding and locked position in which each holding pin 12 is heldcompletely in the locking section 18 of the recess 15 if the drill rod10 has not already been moved into this correct position in the abovedescribed contact with the contact surface 9.

[0034] In the final holding and locking position (see FIGS. 2 and 8) thedrill rod 10 is held by the holding pins 12 in the quarter-turn lock andis protected against turning by the locking teeth 24. The drillingforces which occur on the drill rod 10 in the peripheral direction actsuch that the holding pins 12 continue to be pressed into the lockingsections 18. The peripheral forces which occur when the drill rod 10 isrotated against the drill direction are supported by the locking teeth24 so that the drill rod 10 can neither loosen nor release from itsfixation on the carrier part 4.

[0035] To remove the drill rod 10 in the aforementioned manner thelocking carrier 23 pulls the locking teeth 24 out of their lockingengagement in the recesses 15 so that the drill rod 10 is turnedrelative to the carrier part 4 and the holding pins 12 and can beremoved from the carrier part 4 and the interchangeable holder 1.

[0036] One alternative configuration of the locking teeth 23 is shown inFIG. 9. The locking tooth 24 contains a shaft 34 with reduced thicknessand a head 35 with a bead 36 which projects laterally against theholding pin 12 and in the locked position adjoins it. The shaft 34 isheld with play 34 in the opening 22; this prevents the fine drilledmaterial from jamming the locking tooth 24 in the opening 22.

[0037] Drilled material can be removed for example via a suction fanwhich is connected to the interchangeable holder 1 and which can exhaustthe drilled material for example via openings 37 in the hollow shaft 2.

[0038] The bevelled side edge 20 of the recess 15 is formed either overthe entire depth of the entry section 17 (see FIGS. 6 and 8) or it formsonly one front, funnel-like insertion bevel of the left side of theentry section 17, which side runs then parallel to the axis 8 ofrotation or the lengthwise axis of the drill rod 10 (see FIG. 9). Acomparable bevel can also be formed on the right side of the entrysection 17 in order to improve the funnel action when the locking tooth24 is inserted.

[0039] The angle a between the beveled side edge 20 and the lineparallel to the axis 8 of rotation is preferably roughly 30° to 45°, butif necessary it can also be chosen to be smaller or larger.

[0040] The described interchangeable holder is suitable for hollowdrills for different materials such as concrete, tile, wood or metal andcan be mounted on the shaft 2 on the drilling machine by a connectingmeans 38, for example a screw thread.

REFERENCE NUMBER LIST

[0041]1 interchangeable holder

[0042]2 shaft

[0043]3 drill hole

[0044]4 carrier part

[0045]5 stiffening

[0046]6 front end

[0047]7 outside wall

[0048]8 axis of rotation

[0049]9 contact surface

[0050]10 drill rod

[0051]11 base end

[0052]12 holding pin

[0053]13 drill hole

[0054]14 drill hole

[0055]15 recess

[0056]16 end face

[0057]17 entry section

[0058]18 locking section

[0059]19 locking projection

[0060]20 side edge

[0061]21 base

[0062]22 opening

[0063]23 locking carrier

[0064]24 locking tooth

[0065]25 bearing opening

[0066]26 helical spring

[0067]27 back

[0068]28 holding collar

[0069]29 end face

[0070]30 cover sleeve

[0071]31 journal

[0072]32 recess

[0073]33 bevel

[0074]34 shaft

[0075]35 head

[0076]36 bead

[0077]37 opening

[0078]38 connecting means

1. Interchangeable holder for hollow drills, containing a carrier part(4) for end accommodation of the base end (I 1) of the drill rod (10) ofthe hollow drill, and a holding means (12) for retaining engagement ofthe carrier part (4) on the assigned recesses (15) which are made in thewall of the drill rod (10) on its base end (11), characterized in thatthe carrier part (4) has an end annular contact area (9) foraccommodating drill rods (10; 10′, 10″) with different diameters andthat there is a locking means (24) which together with the holding means(12) is active over the width of the annular contact area (9) in orderto keep locked in the centered position the drill rod (10; 10′; 10″)which is held by the holding means (12) and which has been placedagainst the contact area (9).
 2. Interchangeable holder as claimed inclaim 1, wherein the holding means has at least two and especially threeroughly radially arranged holding pins (12) for bayonet-like retainingengagement in the assigned recesses (15) on the base end (11) of thedrill rod (10; 10′, 10″).
 3. Interchangeable holder as claimed in claim1 or 2, wherein the locking means for each holding pin contains amovable locking tooth (24), and wherein the locking teeth (24) forlocking the drill rod (10; 10′, 10″) which is held by the holding pins(12) can be extended out into the recesses (15).
 4. Interchangeableholder as claimed in claim 3, wherein each locking tooth (24) whichextends roughly over the free length of the holding pin (12) can beextended through a slotted opening (22) which has been formed in thecontact surface (9) of the carrier part (4) in the axial direction intothe position which borders the holding pin (12).
 5. Interchangeableholder as claimed in claim 3 or 4, wherein the annular contact area (9)or the annular end contact surface (9) of the carrier part (4) isbordered by an outer boundary (7) and an inner boundary (6), the holdingpins (12) are each supported on the outside boundary (7) and the insideboundary (6) and each locking tooth (24) extends in an arrangement whichis offset parallel to its holding pin (12) roughly over the free lengthof the holding pin (12).
 6. Interchangeable holder as claimed in one ofclaims 1 to 5, wherein a locking carrier (23) which is supported to beaxially movable on the central shaft (2) of the carrier part (4)contains the locking means or the axially projecting locking teeth (24).7. Interchangeable holder as claimed in claim 6, wherein the lockingcarrier (23) is pretensioned elastically against the carrier part (4) inthe locked position.
 8. Interchangeable holder as claimed in one ofclaims 3 to 7, wherein each locking tooth (24) is rounded or beveledtowards its end face (29).
 9. Interchangeable holder as claimed in oneof claims 3 to 8, wherein each recess (15) on the drill rod (10) has anentry section (17) for the holding pin (12) and the locking tooth (24)and wherein the entry section (17) has at least one side edge (20) whichis tilted towards the direction of motion of the locking tooth (24). 10.Interchangeable holder as claimed in one of claims 2 to 9, wherein eachholding pin (12) is held stationary in the carrier part (4) or in theinner boundary (6) and in the outer boundary (7) in the assigned holes(13 and 14).
 11. Interchangeable holder as claimed in claim 10, whereinfor each holding pin (12), coaxial through holes (13′, 14′) are formedin the opposite section of the carrier part (4).
 12. Interchangeableholder as claimed in one of claims 1 to 11, wherein there is a catchmeans (31, 32) for fixing the opened locking carrier on the carrier part(4) in the catch position.
 13. Interchangeable holder as claimed in oneof claims 1 to 12, wherein the shaft (2) has a connection (38) for adrive means, especially a drilling machine.
 14. Interchangeable holderas claimed in one of claims 1 to 13, wherein the shaft (2) is madehollow and has a suction connection (37).
 15. Hollow drill for fixing onan interchangeable holder, the drill rod of the hollow drill having onthe base end opposite the drill tip recesses for producing bayonet-likeretaining engagement to the holding means of the interchangeable holderand each recess having an entry section for the holding means, whereinthe entry section (17) has at least one side edge (20) tilted to theaxis (8) of rotation.
 16. Hollow drill as claimed in claim 15, whereinthe tilted side edge (20) is bevelled and/or rounded.
 17. Hollow drillas claimed in claim 15 or 16, wherein the entry section (17) contains alocking section (18) and the tilted side edge (20) is opposite thelocking section (18).